Study Design Cross-sectional, controlled laboratory study. Background Postural control following anterior cruciate ligament reconstruction (ACLR) primarily has been investigated during static single-leg balance tasks. Little is known about dynamic postural control deficits post-ACLR. Objectives To compare dynamic postural control (bilaterally) in individuals who have undergone ACLR and in healthy controls, and to evaluate the relationship between dynamic postural control and self-reported and objective function. Methods Ninety-seven participants (66 male; median age, 28 years) 12 months post-ACLR and 48 healthy controls (20 male; median age, 30 years) underwent balance assessment using a Nintendo Wii Balance Board during a single-leg squat. Center-of-pressure (CoP) path velocity, as well as CoP amplitude and standard deviation, in both mediolateral (ML) and anteroposterior (AP) directions were recorded. Self-reported function was assessed with the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC), while hop for distance was used to evaluate functional status. Results Compared to healthy controls, the ACLR group had greater mean CoP path velocity (16% higher, P = .004), ML range (23%, P<.001), ML SD (28%, P<.001), AP range (14%, P = .009), and AP SD (15%, P = .013), indicating worse dynamic balance post-ACLR. Dynamic balance performance was similar between the ACLR limb and the uninjured contralateral limb. The AP SD was weakly associated with hop performance (β = -.2, P = .046); no balance measures were associated with IKDC score. Conclusion Individuals who have undergone ACLR demonstrate impaired dynamic balance bilaterally when performing a single-leg squat, which may have implications for physical function and future injury risk. Routine dynamic balance assessment may help identify patients who could benefit from targeted neuromuscular training programs to improve objective function and potentially lower reinjury risk. J Orthop Sports Phys Ther 2016;46(5):357-364. Epub 21 Mar 2016. doi:10.2519/jospt.2016.6305.